Studies have shown an association between the risk of autism spectrum disorder and vitamin D insufficiency. In this latest study, 109 children with autism spectrum disorder were randomized to receive four months of vitamin D3 supplementation or a placebo.

"Autism symptoms--such as hyperactivity, social withdrawal, and others--improved significantly following vitamin D3 supplementation but not after receiving placebo," said Dr. Khaled Saad, lead author of the Journal of Child Psychology and Psychiatry study.